Drive mechanism for two coaxial calendar members in watch movement

ABSTRACT

A drive mechanism for two coaxial calendar members meant to rotate in stepwise manner about their common axis in a watch movement, comprising a drive member provided with two fingerpieces for actuating one of each of the calendar members, a calendar wheel connected to the gear-train and coaxial with the drive member, a coupling with angular play between the calendar wheel and the drive member, a cam rigidly connected to the drive member, a lever operating in concert with the cam, and a spring acting on the lever such that it will ensure an instantaneous jump of the two calendar members by rotation of the drive members after the latter has been brought into a given orientation by the calendar wheel. The invention is further characterized in that the contour of the cam is provided with a retaining notch operating in concert with the lever and limiting the rotation of the drive member under the influence of the spring.

United States Patent [191 Zaugg et al.

[ June 25, 1974 1 DRIVE MECHANISM FOR TWO COAXIAL CALENDAR MEMBERS IN WATCH MOVEMENT [75] Inventors: Roland Zaugg, Grenchen; Kurt Schaller, Lengnau; Alphonse Bron, Bassecourt, all of Switzerland [73] Assignee: A. Schild S.A., Grenchen,

Switzerland 22 Filed: Sept. 24, 1973 [21] Appl. No.: 400,140

[30] Foreign Application Priority Data Primary Examiner-George H. Miller, Jr. Attorney, Agent, or Firm-Stevens, Davis, Miller & Mosher [5 7] ABSTRACT A drive mechanism for two coaxial calendar members meant to rotate in stepwise manner about their common axis in a watch movement, comprising a drive member provided with two finger-pieces for actuating one of each of the calendar members, a calendar wheel connected to the gear-train and coaxial with the drive member, a coupling with angular play between the calendar wheel and the drive member, a cam rigidly connected to the drive member, a lever operating in concert with the cam, and a spring acting on the lever such that it will ensure an instantaneous jump of the two calendar members by rotation of the drive members after the latter has been brought into a given orientation by the calendar wheel. The invention is further characterized in that the contour of the cam is provided with a retaining notch operating in concert with the lever and limiting the rotation of the drive member under the influence of the spring.

10 Claims, 3 Drawing Figures PAIENTEDJUNZSlQM SHEU 1 IF 2 FIG.

PATENTEI] JUN2 51974 SHEEI 2 0F 2 FIG.2

DRIVE MECHANISM FOR TWO COAXIAL CALENDAR MEMBERS IN WATCH MOVEMENT BACKGROUND OF THE INVENTION 1. Field of the Invention Drive mechanisms providing the sudden commutation of a date-indicating member and of a day-of-theweek indicating member in calendar watches are known. However, as regards most calendar mechanism in wrist-watches providing both date and day, at least one of these displays changes progressively.

The purpose of the present invention is to create a drive mechanism for wrist-watches provided with coaxial date and day indicating members. Such a mechanism shall ensure instantaneous commutation of those members, each advancing by one step, so that an excessive jump by two steps can be avoided. Another purpose of the invention consists in achieving a mechanism by means of a simple and compact construction. Lastly, the invention also aims to add the feasibility of effecting a date correction the moment the jump has oc curred without thereby running the risk of blocking the movement.

2. Summary of Invention To that end, the object of the invention is a drive mechanism for two coaxial calendar members meant to rotate in stepwise manner about their common axis in a watch movement, comprising a drive member provided with two finger-pieces for actuating one of each of the calendar members, a calendar wheel connected to the gear-train and coaxial with the drive member, a coupling with angular play between the calendar wheel and the drive member, a cam rigidly connected to the drive member, a lever operating in concert with the cam, and a spring acting on the lever such that it will ensure an instantaneous jump of the two calendar members by rotation of the drive members after the latter has been brought into a given orientation by the calendar wheel. The invention is further characterized in that the contour of the cam is provided with a retaining notch operating in concert with the lever and limiting the rotation of the drive member under the influence of the spring.

DESCRIPTION OF THE DRAWING The attached drawing illustratively shows an embodiment of the mechanism of the invention, wherein:

FIG. I is a top view, certain parts having been removed;

FIG. 2 is a plan view from the bottom of the assembly plate, with cam and commutation lever; and

FIG. 3 is a section along line Il II of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT 1. Assembly The mechanism to be described below with respect to the preferred embodiment is contained in a wristwatch movement of circular shape. A bottom plate 1 supports a date or crown ring 2 and an hour-wheel 3 ensures the pivoting of a day-star 4 provided with a display disc 5 extending at the same level as crown 2. As is the case for certain known mechanisms, day-star 4 is provided with fourteen teeth and the drive mechanism is made so as to rotate this star step by step each corresponding to two steps of its own teething while commutation takes place. Ordinarily the two members 2 and 4 are held in place by the two jumpers 6 and 7 pivoting about a common axis and actuated by the superposed spring blades 9 and 9'. The two jumpers 6 and 7 extend on either side of axis 8 and one of them acts in a centripetal manner so as to mesh with the teeth of star 4, whereas the other acts in a centrifugal manner so as to mesh with the teeth of crown 2; it is clear that the two springs 9 and 9' are forced to bend-when either of the jumpers moves away from the therewith cooperating toothing.

The drive mechanism of members 2 and 4 is mounted on an assembly plate 10 fastened by two screws 11 to bottom plate 1. The precise positioning of this assembly plate is obtained from head 12 cut in assembly plate 10, this head being housed in a corresponding recess of the bottom plate, and from the head of the stud 26, as shown further below. Assembly platel0 is blanked together with a lateral arm 13 which is folded back at a right angle and forms a spring ensuring commutation. This assembly plate 10 supports foremost a wheel-andpinion 14. A stud 15 for pivoting wheel-and-pinion I4 is force-fitted or otherwise set in an aperture of assembly plate 10, as shown in FIG. 3. Its flat head ensures the axial direction position of wheel-and-pinion 14. The latters wheel meshes with the hour-wheel 3 whereas the pinion drives a calendar wheel 16 performing one revolution every 24 hours. This calendar wheel 16 rotates about a cylindrical shoulder in hub 17 which rotates in an aperture 18 of assembly plate 10. As seen in FIG. 3, this hub is provided with several shoulders of various diameters. At its upper end, it bears a fingerpiece 19 force-fitted around an annular rib below which there is a second lateral finger-piece 20 which is blanked and stamped together with hub 17 and equipped with a catch 21 on its inner side. Circular shoulder 22 stretches below finger-piece 20 and ensures the rotation of wheel 16; further below there is a shoulder penetrating aperture 28. Hub 17 is provided at its lower end with a last shoulder on which is forcefitted a cam 23 with plan contour shown in dotted line in FIG. I. The set of components l7, l9 and 23 constitutes a kind of two-finger ratchet, the fingers l9 and 20 extending approximately diametrically opposite from each other though at different levels. AS, shown in FIG. I, the lengths of those fingers also are different.

The functions of these fingers will be explained further below, but for the present it will be observed that catch 21 penetrates a circular arcuate slot 24 of almost in wheel 16. FIG. 3 shows that the force-fit of cam 23 to hub 17 ties the drive member to the assembly plate 10. Lastly plate 10 also bears (see FIG. 2) a lever 25 pivoting about stud 26, similar to stud 15. Its foot therefore is force-fitted into an aperture of assembly plate 10 and its head keeps lever 25 axially in place. The head of stud 26 is thicker than that of stud l5 and is used as a positioning element for assembly plate 10. During assembly, this head enters a cylindrical recess in the bottom plate. It is during assembly that the drive mechanism l7, 19, 23 is accurately positioned and its rotation is ensured. At that time, the central bore of hub 17 is placed on pin 27 projecting from the bottom plate. The axis of rotation for hub 17 and wheel 16 therefore is determined by pin 27 rather than by aperture 18, which latter only serves for assembly.

Cam 23 comprises a spirally ascending slope 28 and a descending slope 29, the shape of which will be discussed further below. An intermediate slope 33 and a notch 30 are located between those first mentioned slopes. These components of cam 23 are meant to operate in concert either with the extreme beak 31 of lever 25 or with boss 32 in the rear of the beak at a distance equal to that between the bottom of the descending slope 29 and notch 30.

2. Operation The above described mechanism operates as follows. Because of the presence of wheel-and-pinion 14 between calendar wheel 16 and hour-wheel 3, the latter two wheels rotate in the same sense and are continuously driven by the movement. Starting from the position shown in FIG. 1, the rear end of slot 24 will, after several hours of rotation of wheel 16, press against catch 21. Drive ratchet 17, 19, 23 then will be coupled to calendar wheel 16 and from that time will rotate together with this wheel. The spiral part 28 of the cam 23 then passes underneath boss 32 of lever 25 pivoting leftwards in P16. 1 and thereby progressively energizing spring 13. Then beak 31 presses against the spiral part 28. This energization lasts about fourteen hours until beak 31 is at the highest point of the cam, immediately in the rear of the strongly sloping part marking the beginning of the descending slope 29. Ratchet 17, 19, 23 then will be pushed by spring 13 and will rotate suddenly. Finger-piece l9 enters the path of one of the teeth of star 4. Under the influence of spring 13 acting on lever 25, finger-piece 19 rotates this star until jumper 7 has passed by two tooth-spaces of toothing 4. Finger-piece 20 also actuates member 2 by driving one of its teeth in such manner that jumper 6 passes into the next tooth-space. At this instant the cam rotation is such that beak 31 will be in that part of the cam which is nearest the axis at the end of slope 29. Under the influence of the acquired energy, the cam nevertheless continues rotating and boss 32 of lever 25 penetrates notch 30, causing butting between lever and cam. The drive organ remains locked in the orientation shown in the drawing. Therefore the described mechanism causes an instantaneous jump of both indicating members while making use only of one spring and one drive member, the latter being provided with two fingerpieces almost diametrically opposite each other. The drive member being locked at the end of its motion, each of the finger-pieces retains the calendar member it controls, thus eliminating the risk of a double jump of that member. It will be observed from FIG. 1 that finger-pieces 19 and 20 remain in the path of the teeth of the date crown or of the day star when the drive member is blocked in the position shown. On the other hand, while beak 31 (FIG. 2) presses against the cam at a point located beyond its center and hence tends to make it rotate in the counterclockwise sense, boss 32 v mechanism and which acts directly on the date-ring. The motion of the latter in the clockwise sense causes a rotation of the drive member by the intermediary of finger-piece 20, but this rotation is only of slight amplitude: it is such as required for making the tooth behind finger-piece 20 pass beyond the latter. Because slot.24 extends beyond finger-piece 20 in the position shown in FIG. 1, this displacement of the drive-finger is feasible without interfering with the calendar wheel and consequently without the gear-train possibly blocking correction-setting. lf correction occurs at this moment, the motion of finger-piece 20 causes cam rotation, so that boss 32 ascends along the flank of notch 30. Under the influence of spring 13, the cam subsequently returns to its rest position. The conditions under which boss 32 presses against notch 30 and beak 31 rests between slopes 29 and 33 are such that locking is achieved which prevents any excessive rotation between those two pieces.

The described mechanism holds the advantage of simplified construction. Assembling all parts is performed on assembly plate 10 independently of the remainder of the movement, and it will be enough thereafter to place the drive block on the bottom plate to ensure drive. Settings and required adjustments are virtually non-existent. Though the two jumpers 6 and 7 are shown mounted on the bottom plate and stressed by the two springs 9 and 9 pressing against the bent-over tongue 33 which is part of bottom plate 1, one might also make use of a larger assembly plate also bearing jumpers 6 and 7 in another embodiment. It will also be observed that the contour of cam 23 is designed to regulate the angular speed of the drive member as a function of the sequence of operations this drive member must perform. A cam judiciously designed as a function of these criteria allows achieving virtually simultaneous commutation of two coaxial members as different as a day-star with fourteen teeth and supposed to rotate one-seventh of a revolution and a date-crown with inner toothing of which the advance is only one thirtyfirst of a revolution. The above description makes it plain that this problem has been entirely solved in a judicious manner by the present invention.

What is claimed is:

1. A drive mechanism for two coaxial calendar members which rotate stepwise about their common axis in a watch movement, comprising a drive member provided with two finger-pieces for actuating each of said calendar members; a calendar wheel coaxial with the drive member and connected to the gear train of said movement; coupling means with angular play coupling the calendar wheel and the drive member; a cam rigidly connected to the drive member; a lever coupled for operation in concert with the cam; and spring means acting on the lever to ensure an instantaneous jump of the two calendar members by rotation of the drive member when the drive member is brought into a given orientation by the calendar wheel, wherein the contour of the cam is provided with a retaining notch which with the lever engages for limiting the rotation of the drive member under the influence of said spring.

2. A mechanism as defined in claim 1, wherein the drive member and the calendar wheel are connected to each other by a coupling fmger-piece fixed to the drive member and entering an arcuate slot in the calendar wheel.

3. A mechanism as defined in claim 1, further comprising an assembly plate on which the drive member and the lever are mounted and to which the spring is fixedly connected.

4. A mechanism as defined in claim 3, wherein said spring comprises an arm blanked from the assembly plate and bent perpendicularly to the plane of latter.

5. A mechanism as defined in claim 3, wherein the drive member loosely penetrates an aperture of the assembly plate, said driving member having a hub provided with a cylindrical housing placed upon a pivoting pin projecting from a bottom plate of the movement during the fastening of theassembly plate on the bottom plate.

6. A mechanism as defined in claim 1, wherein the retaining notch engages a boss of the lever, the lever being also provided with a beak portion which follows the remainder of the cam contour.

7. A mechanism as defined in claim 2, wherein the drive member and the calendar wheel are connected to each other by a coupling finger-piece fixed to the drive member and entering an arcuate slot in the calendar wheel and wherein the length of said arcuate slot of the calendar wheel is such that at least one of said calendar members may move by one step about its axis when the drive member is blocked by the penetration of the lever boss into the retaining notch of the cam.

8. A mechanism as defined in claim 6, wherein the cam is provided with a spiral slope diverging from its axis starting at said retaining notch, with a descending slope nearing said axis starting at the outer end of the sprial slope, and with a third slope connecting the lower end of the descending slope to the retaining notch.

9. A mechanism as defined in claim 8, wherein said lever pivots about an axis and the distances from the lever pivoting axis to the beak on one hand, and to said boss on the other, are respectively larger and smaller than the distance between the pivoting axis of lever and cam.

10. A mechanism as defined in claim 9, wherein the cam and lever contours are such that the lever beak presses against the inner end of the descending slope when the boss penetrates the retaining notch. 

1. A drive mechanism for two coaxial calendar members which rotate stepwise about their common axis in a watch movement, comprising a drive member provided with two finger-pieces for actuating each of said calendar members; a calendar wheel coaxial with the drive member and connected to the gear train of said movement; coupling means with angular play coupling the calendar wheel and the drive member; a cam rigidly connected to the drive member; a lever coupled for operation in concert with the cam; and spring means acting on the lever to ensure an instantaneous jump of the two calendar members by rotation of the drive member when the drive member is brought into a given orientation by the calendar wheel, wherein the contour of the cam is provided with a retaining notch which with the lever engages for limiting the rotation of the drive member under the influence of said spring.
 2. A mechanism as defined in claim 1, wherein the drive member and the calendar wheel are connected to each other by a coupling finger-piece fixed to the drive member and entering an arcuate slot in the calendar wheel.
 3. A mechanism as defined in claim 1, further comprising an assembly plate on which the drive member and the lever are mounted and to which the spring is fixedly connected.
 4. A mechanism as defined in claim 3, wherein said spring comprises an arm blanked from the assembly plate and bent perpendicularly to the plane of latter.
 5. A mechanism as defined in claim 3, wherein the drive member loosely penetrates an aperture of the assembly plate, said driving member having a hub provided with a cylindrical housing placed upon a pivoting pin projecting from a bottom plate of the movement during the fastening of the assembly plate on the bottom plate.
 6. A mechanism as defined in claim 1, wherein the retaining notch engages a boss of the lever, the lever being also provided with a beak portion which follows the remainder of the cam contour.
 7. A mechanism as defined in claim 2, wherein the drive member and the calendar wheel are connected to each other by a coupling finger-piece fixed to the drive member and entering an arcuate slot in the calendar wheel and wherein the length of said arcuate slot of the calendar wheel Is such that at least one of said calendar members may move by one step about its axis when the drive member is blocked by the penetration of the lever boss into the retaining notch of the cam.
 8. A mechanism as defined in claim 6, wherein the cam is provided with a spiral slope diverging from its axis starting at said retaining notch, with a descending slope nearing said axis starting at the outer end of the sprial slope, and with a third slope connecting the lower end of the descending slope to the retaining notch.
 9. A mechanism as defined in claim 8, wherein said lever pivots about an axis and the distances from the lever pivoting axis to the beak on one hand, and to said boss on the other, are respectively larger and smaller than the distance between the pivoting axis of lever and cam.
 10. A mechanism as defined in claim 9, wherein the cam and lever contours are such that the lever beak presses against the inner end of the descending slope when the boss penetrates the retaining notch. 